The invention relates to bipolar medical instruments in general, and more particularly to improvements in bipolar medical instruments which can be utilized as coagulation instruments as well as for cutting of human and/or other animal tissue.
Bipolar medical coagulation instruments are well known in the art. Reference may be had, for example, to commonly owned U.S. Pat. No. 4,732,149 granted Mar. 22, 1988 for "Bipolar medical coagulation instrument" and to commonly owned German Pat. No. 34 09 061 granted Apr. 25, 1985. Such instruments can also be used for cauterizing if the exposed front end portions of their electrodes can convey currents which suffice to actually cut (by burning or searing) selected cells of tissue. It is then important that the front end portions of the electrodes be capable of standing large currents and that their mutual spacing remain constant, i.e., that such spacing cannot be changed in actual use of the instrument. The cutting action of such instruments is due to penetration of highly concentrated electrical oscillation energy into the tissue between the front end portions of the electrodes so that the tissue acts as a resistor and is heated with attendant destruction of selected cells.
Commonly owned German Pat. No. 32 45 570 (granted Jun. 27, 1985) discloses a bipolar coagulation instrument wherein the front end portions of the electrodes are inclined with respect to the adjacent intermediate portions of the respective electrodes in order to permit more convenient observation of the tissue which is to be treated. Such bending of the front end portions increases the likelihood of changes of orientation of the front end portions relative to each other; the changes of orientation entail a movement of the tips of the front end portions toward or away from each other with attendant pronounced changes in the coagulating or cutting action of the instrument. The patent proposes to avoid such changes of orientatuon by providing the intermediate portions of the electrodes with minute protuberances which extend into complementary recesses of a sleeve serving as a handle and surrounding the intermediate portions of the electrodes. The rear end portions of the electrodes extend beyond the handle and can be inserted into the socket of a plug at the end of a cable which, in turn, is connected to a high-frequency generator. Reference may be had to FIGS. 7 and 12 of German patent No. 32 45 570. Once used, the instrument of this German patent is or can be discarded; all that is necessary is to extract the terminals from the socket and replace the once used instrument with a new instrument. It has been found that the ability of the handle to hold the electrodes against angular and/or axial and/or other movements relative to each other is rather limited in spite of the provision of aforementioned minute protuberances and recesses. The same holds true for the manner of preventing rotation and/or other undesirable movements of electrodes relative to the handle of the instrument which is described and shown in the aforementioned commonly owned German Pat. No. 34 09 061.